Inference for Quantitative Data: Means unit test
A test on this unit alone, marked as a percentage and a letter grade — for the test your class is actually sitting, rather than for May. Answer everything, then submit once: seeing the answer to question 3 before attempting question 4 makes the final percentage meaningless.
One-sample t-test statistic
One-sided p-value from two-sided output
Checking normality from a sample
Degrees of freedom for one sample
Conditions for t procedures
Deciding one-sample or two-sample
Interpreting the magnitude of t
Sample size for a mean
Checking Normality from the sample graph
Shape of the t distribution
Robustness of t procedures
Standard error of the mean
Short answer 1. Define or explain: Degrees of freedom, two samples
3 ptsShort answer 2. Define or explain: Confidence interval for a difference of means
3 ptsShort answer 3. Define or explain: Reading a t-table
3 ptsShort answer 4. Define or explain: How robust t procedures actually are
3 ptsFree response
5 ptsA researcher wants to know whether a new study-skills workshop improves performance on a standardized reading test. Twenty students were randomly assigned to attend the workshop and twenty comparable students were randomly assigned to a control group. The resulting test scores are summarized below. Workshop: n = 20, mean = 78.4, s = 6.2 Control: n = 20, mean = 72.0, s = 7.8 Assume the conditions for inference are met.
A. State the hypotheses for a test of whether the workshop increases mean test score.
B. Calculate the value of the test statistic.
C. Determine the p-value and state your conclusion at the α = 0.05 level.
D. Construct and interpret a 95 percent confidence interval for the difference in mean test scores.